Evolved Universal Mobile Telecommunication System Terrestrial Radio Access Network (E-UTRAN), also known as Long Term Evolution (LTE) network, delivers information at a high data transmit rate with low latency. Such an E-UTRAN has been built over a UMTS terrestrial radio access network (UTRAN), also known as wideband code division multiple access network (WCDMA). For example, E-UTRAN cells may be overlaid on UTRAN cells.
User equipment may have poor reception signal quality due to many reasons. For example, when user equipment is located at an edge of one E-UTRAN cell or when a serving base station of an E-UTRAN cell has large load, the user equipment may have poor reception signal quality. In this case, it might need to redirect the user equipment between heterogeneous networks, for example, the E-UTRAN to the UTRAN.